Accumulated Other Comprehensive Loss (Reclassifications) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Gains (losses) on cash flow hedges
Revenues		$ 839,031	$ 869,541	$ 2,519,506	$ 2,641,113
Interest expense, net		(22,294)	(20,165)	(62,394)	(65,200)
(Benefit) provision for income tax		23,197	42,676	93,615	145,574
Net income		70,105	93,876	190,929	335,445
Pension and Postretirement Benefit Plans
Benefit from income tax		(3,243)	(4,219)	(10,362)	(12,001)
Reclassification out of Accumulated Other Comprehensive Loss
Gains (losses) on cash flow hedges
Revenues	[1]	443	211	(290)	1,039
Cost of sales	[1]	(301)	(41)	69	544
Interest expense, net	[1]	(507)	(507)	(1,521)	(1,521)
Total before tax	[1]	(365)	(337)	(1,742)	62
(Benefit) provision for income tax	[1]	(144)	(132)	(679)	15
Net income	[1]	(221)	(205)	(1,063)	47
Gains (losses) on available for sale securities
Interest expense, net	[1]	(1,125)	1,085	(1,126)	1,043
(Benefit) provision for income tax	[1]	(433)	401	(433)	385
Net of tax	[1]	(692)	684	(693)	658
Pension and Postretirement Benefit Plans
Transition credit	[1],[2]	2	2	6	7
Prior service costs	[1],[2]	(40)	(60)	(123)	(179)
Actuarial losses	[1],[2]	(9,168)	(11,596)	(29,036)	(33,193)
Total before tax	[1],[2]	(9,206)	(11,654)	(29,153)	(33,365)
Benefit from income tax	[1],[2]	(3,243)	(4,219)	(10,362)	(12,001)
Net of tax	[1],[2]	$ (5,963)	$ (7,435)	$ (18,791)	$ (21,364)

[1] Amounts in parentheses indicate reductions to income and increases to other comprehensive income (loss).

[2] Reclassified from accumulated other comprehensive loss into selling, general and administrative expenses. These amounts are included in the computation of net periodic costs (see Note 10 for additional details).